Caption: Schistosome parasite. Scanning electron micrograph (SEM) of sensory papillae on the surface of a schistosome (Schistosoma sp.) cercaria. This fluke is the cause of the disease schistosomiasis (bilharzia). The cercarial stage lives in lakes and rivers, penetrating the skin of humans in the water. It locates its host by following trails of chemicals secreted from human skin. These are detected by the sensory papillae. After entering a human it matures to the adult form, then migrates to the veins surrounding the bladder or intestines. Untreated schistosomiasis causes kidney and liver damage. Magnification: x2,900 at 5x7cm size. x5000 at 4x5 inch size.